The present invention relates to a chemical scrubber unit and, more particularly, to a chemical scrubber unit for containing and neutralizing toxic, corrosive gases generated under certain conditions within a primary electrochemical cell.
Primary electrochemical cells are generally well known and understood by those skilled in the art. One particularly useful primary electrochemical cell, especially for high current drain applications, is a so-called prismatic primary electrochemical cell. Such a cell is described in detail in U.S. Pat. No. 4,086,397, in the names of Franz Goebel and Nikola Marincic, and includes a physically large battery stack enclosed together with an electrolytic solution within a large, generally rectangular metal (e.g., stainless steel) housing. The battery stack as used within the cell comprises a large number of generally rectangular cell components including a plurality of anodes, carbon cathode current collector electrodes, and insulative separators (e.g., of fiberglass) between the anodes and the carbon cathode current collector electrodes. Each anode generally comprises a large rectangular sheet of an oxidizable alkali metal, such as lithium, physically impressed into a supporting metal (e.g., nickel) grid, and each of the carbon cathode current collector electrodes comprises an aggregation of porous, semi-rigid carbon globules or conglomerates physically impressed into a metal (e.g., nickel) current collector grid. A common and preferred electrolytic solution employed in the cell as described above is a cathodelectrolyte solution comprising a reducible soluble cathode such as thionyl chloride and an electrolyte solute such as lithium tetrachloroaluminate dissolved in the thionyl chloride.
By the appropriate selection of the battery cell components and materials, a cell as described above can be constructed to have any one of several possible sizes and energy configurations. A typical cell can, for example, have exterior dimensions of approximately 18 inches (height).times.13 inches (width).times.10 inches (depth), a weight of 156 pounds, an ampere-hour capacity rating of 10,000 ampere-hours, and a nominal discharge current of 40 amperes.
During the discharge cycle of a primary electrochemical cell having the above-described characteristics, it is possible under certain adverse conditions, such as abnormally high operating temperature conditions, for large amounts of gases to be generated in the cell as a result of the existence of the adverse conditions. These gases include sulfur dioxide and thionyl chloride and result in an increase in the internal pressure within the housing of the cell. While it is possible to design the housing so as to withstand the increased internal pressure resulting from the above-mentioned condition, this solution may be impractical or prohibited by design constraints of a particular cell application. It may also be possible to vent the gases to the atmosphere by way of a pressure relief valve so that the pressure is limited to a value below the safe structural limits of the cell housing. However, the gases (sulfur dioxide and thionyl chloride) are both toxic and corrosive. It may be desirable therefore to avoid this solution for applications where people are expected to be present or where the cell is to be used in conjunction with, or proximate to, apparatus which might be adversely affected or otherwise damaged by the corrosive nature of the gases.